Early embryonic development and cell differentiation

Question 1

What does the umbilical cord surrounded by

Answer 1

Layer of amnion

Question 2

What does the umbilical car contain

Answer 2

• umbilical vein and arteries
• Allantois
• Vitello-intestinal duct
• Mesoderm from; amnion, yolk sac, and connecting stalk

Question 3

Where does the extra-embryonic coelom persist in the umbilical cord
-what is it important in

Answer 3

Proximally

-Important in the development of the gut

Question 4

What does the pericardial cavity house

Answer 4

The heart

Question 5

What does the pleural cavity house

Answer 5

The lungs

Question 6

What does the peritoneal cavity house

Answer 6

The gut tube

Question 7

When do cells differentiate

Answer 7

During embryogenesis

Question 8

What is ‘cleavage’

Answer 8

Process in which the zygote divides into multiple cells

Question 9

What does cleavage trigger

Answer 9

embryonic differentiation

Question 10

What process produces the three germ layers

Answer 10

Gastrulation

Question 11

What are blastomeres

Answer 11

Cells which make up the blastocyst

Question 12

What does the inner cell mass make

Answer 12

trilaminar disc

Question 13

What does the trilaminar disc make

Answer 13

• mesoderm
• ectoderm
• endoderm

Question 14

What does the endoderm form

Answer 14

• Epithelia of internal surfaces

e. g. respiratory system and urinary system

Question 15

What does the ectoderm form

Answer 15

• Neuroectoderm
  e. g. neural crest and the neural tube
• Surface of the body
  e. g. skin, hair, nails, mammary glands and pituitary

Question 16

What does the mesoderm form

Answer 16

• Paraxial mesoderm (e.g. muscles of head, trunk, skeleton, dermis and connective tissue)
• Head mesoderm (e.g. skull, connective tissue and dentin)
• Intermediate mesoderm (e.g. urinogenital systen, ducts and accessory glands)
• Lateral mesoderm (e.g. connective tissue and muscle of viscera, serous membranes, heart, blood, spleen and adrenal cortex)

Question 17

What is regulative development

-What does this do

Answer 17

Involves interaction of adjacent cells, within embryonic fields.
-Gives flexibility to differentiation

Question 18

What are the two important characteristics of stem cells

Answer 18

• unspecialised and can divide repeatedly over long periods

- Under certain conditions, can be induced to differentiate into cells with special function

Question 19

What are totipotent stem cells

Answer 19

Can differentiate into all cell types, plus extra embryonic cells e.g. zygote

Question 20

What are pluripotent stem cells

Answer 20

Can give rise to all 3 germ layers but not embryonic (e.g. cells of the inner cell mass of the blastocyst where embryonic stem cells are derived)

Question 21

What are multipoint stem cells

Answer 21

Can give rise to a restricted number of different cell types

Question 22

What happens in therapeutic cloning or somatic nuclear transfer

Answer 22

• Nuclei from adult cells and introduce them into enucleated oocytes
• Oocytes are stimulated to differentiate into blastocysts, and ES cells are harvested
• BEcause cells are derived from host, they are not compatible genetically and because fertilization is not involved, the technique is less controversial